1. Field of the Invention
The invention relates to plate-type falling film condensers which incorporate a blow down concentrator.
2. Discussion of the Prior Art
Plate-type falling film heat exchangers are highly effective and are widely used in various industries. Heat exchangers of this type have been disclosed in U.S. Pat. Nos. 3,332,469; 3,351,119; 3,366,158 and 3,371,709. Heat exchange elements made up of pairs of plates secured together around their edges and having opposed dimples to strengthen the element against deformation are described in U.S. Pat. No. 3,512,239 which discloses a method of making such elements.
Falling film heat exchangers are used as evaporators to vaporize liquid flowing as a film or as condensers to liquify steam or other vapor by the transfer of heat therefrom to a falling liquid film. In an evaporator the heating of the liquid is the desired result. In a condenser the heating of the liquid is an unavoidable consequence of the transfer of heat from the condensing vapor. The heating of the coolant liquid in condensers and the consequent loss of its ability to cool has been tolerated in the past.
An evaporative condenser which condenses vapor such as steam by evaporative cooling uses a circulating coolant medium, usually water. As the water circulates, it not only gets warmer but also develops an increasing concentration of dissolved solids.
Some of the circulating water can be replaced with fresh make-up water as some of the water carrying the dissolved solids is removed as waste to a sewer or the like, keeping the circulating water of good enough quality to avoid scaling and deposits on the heating surface, but environmental considerations have made disposal of the solids-bearing waste water troublesome. In many cases this waste water goes to a separate evaporator where it is concentrated to the point where it can be used as landfill.